Hypersensitivity pneumonitis

Definition:
An inflammation in the lungs caused by exposure to an allergen (foreign substance), usually organic dust. This dust may come from animal dander, molds, or plants.

Alternative Names:
Extrinsic allergic alveolitis; Farmer's lung; Mushroom picker's disease; Humidifier or air-conditioner lung; Bird breeder's lung

Causes, incidence, and risk factors:
This is usually an occupational disease in which exposure to organic dusts, fungus, or molds leads to acute and over time, chroniclung disease. Exposure may also occur in the home, from fungus (molds) present in humidifiers, heating systems, and air conditioners. Some people (for example, bird owners) may have hobbies that can lead to exposure. Acute illness may occur 4 to 6 hours after the exposure, once the person has left the area where the allergen is present. Chronic illness with changes seen on chest X-ray may develop with continued exposures. The chronic form of this disease may lead to pulmonary fibrosis (a scarring of the lung tissue that is often not reversible).


Review Date: 10/21/2001
Reviewed By: David Kaufman, M.D., Pulmonary & Critical Care Medicine, University of Pennsylvania Medical Center. Review provided by VeriMed Healthcare Network.

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